Conventionally, a convoy travel technique is known for organizing a convoy of vehicles, in which information is transmitted from vehicle to vehicle through vehicle-to-vehicle communication from a leader vehicle to its following vehicles, for the control of the following vehicles. That is, the following vehicles are controlled to follow the leader vehicle of a convoy by transmitted information from the leader vehicle, thereby making up a group of vehicles traveling as a convoy.
Further, in a patent document 1 (i.e., Japanese Patent Laid-Open No. H11-328584), a vehicle group formation apparatus is disclosed, which splits a convoy of vehicles into two portions to allow a merging vehicle to merge into traffic. When the convoy of vehicles reaches a merge point of the road (i.e., at a part of a road where an on-ramp merges with a main road), the convoy of vehicles is split into a former portion and a latter portion to accommodate the merging vehicle within a gap created between the former portion and the latter portion. More specifically, when the convoy of vehicles approaches the merge point, the vehicle group formation apparatus identifies a convoy vehicle that will “meet” the merging vehicle at the merge point (i.e., a convoy vehicle that reaches the merge point substantially at the same time as the merging vehicle) based on position information that is transmitted directly or indirectly from the merging vehicle. Then, the vehicle group formation apparatus performs a deceleration control for the identified convoy vehicle and other subsequent vehicles (i.e., the latter portion of the convoy of vehicles), to create a gap within the convoy of vehicles such that the merging vehicle may merge into traffic by entering into the gap.
However, the technique in the patent document 1 is problematic, because the technique assumes that all vehicles are equipped with a wireless communicator and capable of transmitting position information. Therefore, vehicles not equipped with a communicator are ignored and the merging of such a non-communicator equipped vehicle at the merge point may be hindered.
Further, the reserving of the gap and the merging of the vehicle within the gap at the merge point may always be allowed by splitting the convoy into two portions (i.e., former/latter groups of convoy vehicles). However, if the merging vehicle does not enter into the gap, splitting of the convoy and deceleration of the latter convoy vehicles is unnecessary. That is, in other words, an unnecessary speed change occurs and the ride comfort of the latter convoy vehicles is compromised.